A Study to Try to Bring Back Radioiodine Sensitivity in Patients With Advanced Thyroid Cancer.
Status:
Recruiting
Trial end date:
2021-12-31
Target enrollment:
Participant gender:
Summary
Thyroid cancers that have spread beyond the neck are not curable. About 30,000 people
worldwide die from thyroid cancer every year. Usually, thyroid cancers get worse because the
cancer cells become more and more abnormal through a process that is called
dedifferentiation.
Radioactive iodine is a standard treatment for this type of thyroid cancer. Patients will
usually receive multiple dose of radioactive iodine over the course of their cancer journey.
Thyroid cancers lose sensitivity to radioactive iodine as the cancer progresses/worsens with
the process of dedifferentiation. When this occurs, the radioactive iodine treatments no
longer work against the cancer and the cancer grows.
Radioactive iodine enters cancer cells through transporter proteins on the outside of the
cancer cell. The transporter proteins that are the most important are the sodium iodide
symporters. As thyroid cancers dedifferentiate, these symporters stop working as well as they
once did. The radioactive iodine can therefore not get into the cancer cells to cause cancer
cell death.
Laboratory research has shown that in thyroid cancer, a protein on the cell called platelet
derived growth factor receptor alpha (PDGFRα) is an important for tumour growth and thyroid
cancer dedifferentiation. PDGFRα helps cancer progression and lowers the ability of sodium
iodine symporters to move radioiodine into cells where it would normal act to kill the cancer
cells. PDGFRα therefore makes thyroid cells resistant to radioactive iodine.
Imatinib is an anti-cancer drug that blocks PDGFRα function. It has been used for many years
to treat other cancers such as leukemia. The investigators who wrote this study believe that,
base on laboratory testing, if thyroid cancer patients are given imatinib whenafter their
cancers have become resistant to radioactive iodine, the imatinib will block PDGFRα. This
will let the sodium iodine symporters work again and move the radioactive iodine into the
cancer cells. This should shrink the tumours. Imatinib would then make the thyroid cancer
cell sensitive to radioactive iodine again. This should shrink the tumours and would mean
longer control of the cancer, helping people with this disease live longer.